Global Modeling of Thermospheric Airglow in the Far-Ultraviolet

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Thursday, April 27, 2017

The Global Airglow (GLOW) model has been updated and extended to calculate ultraviolet light emitted by the upper atmosphere, including during the day, the night, and in the aurora. It can be run using inputs from standard climatological models of the upper atmosphere and ionosphere, or from complex computer models that describe the dynamics of the ionosphere.

Synthetic ultraviolet global images image
Synthetic ultraviolet global images simulated by the TIE-GCM and GLOW models as they would be observed from geostationary orbit (5.6 Earth Radii above the surface) at 47.5° west longitude, midnight GMT, during southern hemisphere summer solstice and high solar activity. Left: atomic oxygen emission at 135.6 nm. Right: molecular nitrogen emissions in the 141–153 nm range from the Lyman-Birge-Hopfield (LBH) bands. Daytime emissions dominate in the sunlit region, but the aurora is strongly visible in the north. The LBH bands do not emit at night, but atomic oxygen does, revealing the structure of the ionosphere.

It computes energetic electron fluxes from both solar and auroral sources, and it contains a chemistry module that calculates the densities of excited and ionized atoms and molecules, and the resulting airglow emission rates. This paper describes the inputs, algorithms, and code structure of the model, and demonstrates example outputs for daytime and the aurora. Simulations of ultraviolet emissions by atomic oxygen and molecular nitrogen, as viewed from geostationary orbit, are shown, and model calculations are compared to observations by the Global Ultraviolet Imager on the TIMED satellite. The GLOW model code is provided to the community through an open-source academic research license.

Submitted to the Journal of Geophysical Research—Space Physics.